• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.599-604
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• 2013

In this study, Ti added Mn-Cu mixed oxide catalysts were prepared by a co-precipitation method and used for the low temperature (< $200^{\circ}C$) selective catalytic reduction (SCR) of NOx with $NH_3$. Physicochemical properties of these catalysts were characterized by BET, XRD, XPS, and TPD. Mn-Cu mixed oxide catalysts were found to be amorphous with a large surface and they showed high SCR activity. Experimental results showed that the addition of $TiO_2$ to Mn-Cu oxide enhanced the SCR activity and $N_2$ selectivity. Ti addition led to the chemically adsorbed oxygen species that promoted the oxidation of NO to $NO_2$ and increased the number of $NH_3$ adsorbed-sites such as $Mn^{3+}$.

• Clean Technology
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• v.16 no.2
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• pp.132-139
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• 2010

The Cu-Mn mixed oxide catalysts with different molar ratios of Cu/(Cu+Mn) prepared by co-precipitation method have been investigated in CO oxidation at $30^{\circ}C$. The catalysts used in this study were characterized by X-ray Diffraction (XRD), $N_2$ sorption, X-ray photoelectron spectroscopy (XPS), and $H_2$-temperature programmed reduction $(H_2-TPR)$ to correlate with catalytic activities in CO oxidation. The $N_2$ adsorption-desorption isotherms of Cu-Mn mixed oxide catalysts showed a type 4 having pore range of 7-20 nm and BET surface area was increased from 17 to $205\;m^2{\cdot}g^{-1}$ with increasing of Mn content. The XPS analysis showed the surface oxidation state of Cu and Mn represented $Cu^{2+}$and the mixture of $Mn^{3+}$ and $Mn^{4+}$, respectively. Among the catalysts studied here, Cu/(Cu+Mn) = 0.5 catalyst showed the highest activity at $30^{\circ}C$ in CO oxidation and the catalytic activity showed a typical volcano-shape curve with respect to Cu/(Cu+Mn) molar ratios. The water vapor showed a prohibiting effect on the efficiency of the catalyst which is due to the competitive adsorption of carbon monoxide on the active sites of catalyst surface and finally the formation of hydroxyl group with active metals.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.6
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• pp.337-341
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• 2016

In this study, $ Ni_{0.79}(Mn_{2.21-x}Cu_x)O_4$ (x=0~0.25) specimens were prepared by using a conventional mixed oxide method. All specimens were sintered in air at $1,200^{\circ}C$ for 12 h and cooled at a rate of $2^{\circ}C/min$ to $800^{\circ}C$, subsequently quenching to room temperature. We investigated the structural and electrical properties of $ Ni_{0.79}(Mn_{2.21-x}Cu_x)O_4$ specimens with variation of CuO amount for the application of NTC thermistors. As results of X-ray diffraction patterns, all specimens showed the formation of a complete solid solution with cubic spinel phase. The relationship between ln ${\rho}$ and the reciprocal of absolute temperature(1/T) for the NTC thermistors was shown linearity, which exhibited the typical NTC thermistor properties. With increasing the amount of CuO, resistivity at room temperature, B-value, and temperature coefficient resistance decreased.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.129-135
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• 2016

CO oxidation was performed with Cu-Mn and Cu-Zn co-precipitated catalysts as differential precipitant, metal ratio and calcination temperature. The effects of differential metal mole ratio and calcination temperature in mixed metal oxide catalyst were investigated with CO oxidation reaction. Physiochemical properties were studied by XRD, $N_2$ sorption and SEM. 2Cu-1Mn with $Na_2CO_3$ catalyst calcined at $270^{\circ}C$ has a large surface area $43m^2/g$ and the best activity for CO oxidation. $Cu_{0.5}Mn_{2.5}O_4$ in XRD peak shows the lower activity than others. The catalytic activity over the catalyst calcined $270^{\circ}C$ displayed the highest conversion, and it was better activity comparing with Pt catalysts CO conversion.

• Journal of the Korean Applied Science and Technology
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• v.33 no.2
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• pp.401-410
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• 2016

The $Pt-Sn/Al_2O_3$ catalysts mixed with metal oxides for propane dehydrogenation were studied. $Cu-Mn/{\gamma}-Al_2O_3$, $Ni-Mn/{\gamma}-Al_2O_3$, $Cu/{\alpha}-Al_2O_3$ was prepared and mixed with $Pt-Sn/Al_2O_3$ to measure the activity for propane dehydrogenation. As standard sample, $Pt-Sn/Al_2O_3$ catalyst mixed with glassbead was adopted. In the case of catalytic activity test after non-reductive pretreatment of catalyst and metal oxide, $Pt-Sn/Al_2O_3$ mixed with $Cu-Mn/{\gamma}-Al_2O_3$ showed higher conversion of 15% and similar selectivity at $576.5^{\circ}C$, compared to conversion of 8% in standard sample. In the case of catalytic activity test after reductive pretreatment of catalyst and metal oxde, $Cu/{\alpha}-Al_2O_3$ showed higer yield than standard sample. But, increase of yield of most of samples after reductive pretreatment was not significant, so it was found that lattice oxygen of $Cu-Mn/{\gamma}-Al_2O_3$ is effective to propane dehydrogenation.

• Journal of the Korean Chemical Society
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• v.61 no.4
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• pp.157-162
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• 2017

In the present study, nanocrystalline mixed metal oxide, $CuMnO_3$ catalyst have been synthesized by mechanochemical method with green chemistry approach. The synthesized catalyst was characterized by analytical techniques including FTIR, XRD, SEM, TEM and BET surface area. The synthesized catalyst shows high surface area is $121.06m^2/g$ with particle size 18 nm. The one pot four component synthesis of substituted 2-phenyl-4(3H) quinazolinone from the reaction of anthranilic acid, benzoyl chloride, hydrazine hydrate and substituted benzaldehyde in presence of $CuMnO_3$ nanocatalyst has been carried out. It affords the corresponding products with high yield (76-95%) in very short reaction time. All the obtained products were characterized with $^1HNMR$, $^{13}CNMR$, FTIR and EIMS.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.709-712
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• 1997

Selective removal of NOx by binary oxide systems of Ba-Cu and Mn-Zr was investigated. These mixed oxides were effective in removing NOx at $400^{\circ}C$ by absorption in or on the solid as nitrate. The reaction was investigated by oxidation of NO which was promoted in the presence of $O_2$ on Mn or Cu sites. Then, the oxidized species were stored in the solid as nitrate ions on Ba or Zr sites.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.1
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• pp.1-8
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• 2017

Cu/Mn/Ce catalysts for water gas shift (WGS) reaction were synthesized by urea-nitrate combustion method with the fixed molar ratio of Cu/Mn as 1:4 and 1:1 with the doping concentration of Ce from 0.3 to 0.8 mol%. The prepared catalysts were characterized with SEM, BET, XRD, XPS, $H_2$-TPR, $CO_2$ TPD, $N_2O$ chemisorption analysis. The catalytic activity tests were carried out at a GHSV of $28,000h^{-1}$ and a temperature range of 200 to $400^{\circ}C$. The Cu/Mn(CM) catalysts formed Cu-Mn mixed oxide of spinel structure ($Cu_{1.5}Mn_{1.5}O_4$) and manganese oxides ($MnO_x$). However, when a small amount of Ce was doped, the growth of $Cu_{1.5}Mn_{1.5}O_4$ was inhibited and the degree of Cu dispersion were increased. Also, the doping of Ce on the CM catalyst reduced the reduction temperature and the base site to induce the active site of the catalyst to be exposed on the catalyst surface. From the XPS analysis, it was confirmed that maintaining the oxidation state of Cu appropriately was a main factor in the WGS reaction. Consequently, Ce as support and dopant in the water gas shift reaction catalysts exhibited the enhanced catalytic activities on CM catalysts. We found that proper amount of Ce by preparing catalysts with different Cu/Mn ratios.

• Journal of the Korean Magnetics Society
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• v.13 no.2
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• pp.47-52
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• 2003

Ferromagnetic tunnel junctions were fabricated by dc magnetron sputtering and plasma oxidation process. The local transport properties of the ferromagnetic tunnel junctions were studied using contact-mode Atomic Force Microscopy (AFM) and the local current-voltage analysis. Tunnel junctions with the structure of sub./Ta/Cu/Ta/NiFe/Cu/Mn$\_$75/Ir$\_$25//Co$\_$70/Fe$\_$30//Al-oxide were prepared on thermally oxidized Si wafers. Al-oxide layers were formed with microwave excited plasma using radial line slot antenna (RLSA) for 5 and 7 sec. Kr gas was used as the inert gas mixed with $O_2$ gas for the plasma oxidization. No correlation between topography and current image was observed while they were measured simultaneously. The local current distribution was well identified with the distribution of local barrier height. Assuming the gaussian distribution of the local barrier height, the ferromagnetic tunnel junction with longer oxidation time was well fitted with the experimental results. As contrast, in the case of the shorter time oxidation junction, the current mainly flow through the low barrier height area for its insufficient oxygen. Such leakage current might result in the decrease of tunnel magnetoresistance (TMR) ratio.

• Journal of the Korean Applied Science and Technology
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• v.23 no.1
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• pp.63-69
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• 2006

Methanol and formaldehyde were produced directly by the partial oxidation of methane. The catalysts used were mixed oxides of late-transition metals, such as Mn, Fe, Co, Ni and Cu. The reaction was carried out at $450^{\circ}C$, 50 bar in a fixed-bed differential reactor. The prepared catalysts were characterized by XRD, TPD and BET apparatus. Of the catalysts, A-Mn0.2-6, which contains 0.2 mole of Mn and calcined at $600^{\circ}C$, showed the best catalytic activity: 3.7% methane conversion, and 30 and 28% methanol and formaldehyde selectivities, respectively. The catalytic activity was changed with the content of Mn and the calcination temperature. Catalytic activity increased with the specific surface areas of the catalysts. With XRD, it was found that the structure of the catalysts are changed with calcination temperature. Through $O_2-TPD$ experiment, it was found that the catalysts showing good catalytic activity showed $O_2$ desorption peak around $800^{\circ}C$.